Display systems, such as liquid crystal display (LCD) systems, LED systems, organic light emitting display (OLED) systems, etc. may be used in a variety of environments. Depending on the use environment and application of the display system, brightness and contrast features of the display system may be of significant value. For example, use of a display system in an outdoor environment or in an environment with high ambient light may require increased levels of contrast and/or brightness to maintain a desired level of viewability.
As an example, typical display systems include an LCD assembly. An LCD assembly may comprise a liquid crystal display cell having a thin film of liquid crystals sandwiched between a pair of transparent electrodes. The LCD cell typically includes a pair of glass plates, the glass plates being sealed together around their respective edges. The glass plates may be assembled with spacers between them to maintain a constant separation distance. Two crossed axis polarizers may be adhered to the respective outside surfaces of the glass plates, one polarizer being adhered to the front of the LCD cell and the other polarizer being adhered to the rear of the LCD cell. When a voltage is applied selectively across the electrodes, the liquid crystal molecules between them may be rearranged or switched in polarization so that light is either transmitted or absorbed in the output polarizer to form characters or graphics.
As an example, LCD assemblies are typically retained against and within a plastic or metal mechanical bezel. The mechanical bezel may decrease the viewable area of the display system, and often may extend outward away from the flat plane of the LCD assembly. The mechanical bezel may also have provisions (holes, mounting bosses, etc) for sensors, actuators, or other devices that can serve as on/off buttons, contrast controls, brightness controls, etc. The manner in which the LCD assembly and the mechanical bezel are mounted together affects the ability of the display to withstand mechanical wear, shock and environmental exposure (e.g., water, humidity, temperature, mechanical movement, or wear, etc.).
In order to improve the ability of the display to withstand mechanical wear, shock and environmental exposure it is known to add a protective layer, also referred to herein as a window overlay. This window overlay may be secured to the outer face of an LCD (or OLED) assembly as an interface between the display system and the viewer. For example, the overlay may be secured to the assembly through use of a mechanical bezel. This mechanical bezel may protrude from the surface of the display resulting in trapping of dirt, sand, salt water, etc. Further, the mechanical bezel may be affected by other environmental conditions, including shock, temperature, water, etc. In addition, the mechanical bezel may limit the aesthetic appeal of the device, and depending on the type of overlay and the use environment, the window overlay may impact the visibility of the displayed image.
The inventors herein have recognized that an improved overlay may be used to improve the environmental robustness and viewing characteristics of a display system. Additionally, the applicability and aesthetic appeal of the display system may be increased. Thus, as described in the disclosure below and as illustrated in the example figures, the inventors have provided methods, processes, systems and apparatus for providing an improved display system with an overlay, including methods, processes, systems and apparatus for bonding an overlay to a display assembly.